<html>
<head>
	<meta charset="UTF-8">
	<meta content="IE=edge" http-equiv="X-UA-Compatible">
	<meta content="initial-scale=1.0, maximum-scale=1.0, user-scalable=no, width=device-width" name="viewport">
	<title>4780：[Usaco2017 Open]Modern Art 2</title>
	<!-- css -->
	<link href="../css/base.min.css" rel="stylesheet">
	<link href="../css/project.min.css" rel="stylesheet">
	
	<!-- favicon -->
	<!-- ... -->
</head>
<body class="page-brand">
	<header class="header header-transparent header-waterfall ui-header">
		<ul class="nav nav-list pull-left">
			<li>
				<a data-toggle="menu" href="#menu">
					<span class="icon icon-lg">menu</span>
				</a>
			</li>
		</ul>
		<a class="header-logo header-affix-hide margin-left-no margin-right-no" data-offset-top="213" data-spy="affix">[Usaco2017 Open]Modern Art 2</a>
		<span class="header-logo header-affix margin-left-no margin-right-no" data-offset-top="213" data-spy="affix">[Usaco2017 Open]Modern Art 2</span>
	</header>
	<nav aria-hidden="true" class="menu" id="menu" tabindex="-1">
		<div class="menu-scroll">
			<div class="menu-content">
				<a class="menu-logo" href="../index.html">BZOJ离线题库</a>
				<ul class="nav">
					<li>
						<a class="waves-attach" data-toggle="collapse" href="#problems">题目</a>
						<ul class="menu-collapse collapse in" id="problems">
							<li>
								<a class="waves-attach" href="../index.html">主页</a>
							</li>
							<li>
								<a class="waves-attach" href="../list.html">题目列表</a>
							</li>
						</ul>
					</li>
					<li>
						<a class="collapsed waves-attach" data-toggle="collapse" href="#about">关于</a>
						<ul class="menu-collapse collapse" id="about">
							<li>
								<a class="waves-attach" href="../about.html">关于此项目</a>
							</li>
						</ul>
					</li>
					
				</ul>
			</div>
		</div>
	</nav>
	<main class="content">
		<div class="content-header ui-content-header">
			<div class="container">
				<h1 class="content-heading">
                [Usaco2017 Open]Modern Art 2                </h1>
                <p>时间限制：10s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：128MB</p>			</div>
		</div>
		<div class="container">
			<section class="content-inner margin-top-no">
				<div class="row">
					<div class="col-lg-13 col-md-13">
						<div class="card margin-bottom-no">
							<div class="card-main">
								<div class="card-inner">
									
                                <h3>题目描述</h3><p><div>Having become bored with standard 2-dimensional artwork (and also frustrated at others copying her w</div>
<div>ork), the great bovine artist Picowso has decided to switch to a more minimalist, 1-dimensional styl</div>
<div>e.Although, her paintings can now be described by a 1-dimensional array of colors of length N(1&le;N&le;</div>
<div>100,000), her painting style remains unchanged: she starts with a blank canvas and layers upon it a&nbsp;</div>
<div>sequence of &quot;rectangles&quot; of paint, which in this 1-dimensional case are simply intervals. Sheuses ea</div>
<div>ch of the colors 1&hellip;Nexactly once, although just as before, some colors might end up being completel</div>
<div>y covered up by the end.To Picowso's great dismay, her competitor Moonet seems to have figured out h</div>
<div>ow to copy even these 1-dimensional paintings, using a similar strategy to the preceding problem: Mo</div>
<div>onet will paint a set ofdisjoint intervals, wait for them to dry, then paint another set of disjoint</div>
<div>&nbsp;intervals, and so on.Moonet can only paint at most one interval of each color over the entire proce</div>
<div>ss. Please compute thenumber of such rounds needed for Moonet to copy a given 1-dimensional Picowso&nbsp;</div>
<div>painting.</div>
<div>
<div>给定一个序列，序列上每个点有一个颜色。每一轮可以选择一些没有交集的区间，将每个区间涂上一种颜色。要求</div>
<div>全程每个颜色最多被涂一个区间，求最少涂多少轮</div>
</div>
<div></div>
<p></p></p><hr/><h3>输入格式</h3><p><div>The first line of input contains N</div>
<div>, and the next N lines contain an integer in the range 0&hellip;N</div>
<div>indicating the color of each cell in the 1-dimensional painting (0 for a blank cell).</div>
<div></div>
<p></p></p><hr/><h3>输出格式</h3><p><div>Please output the minimum number of rounds needed to copy this painting, or -1 if this could not hav</div>
<div>e possibly been an authentic work of Picowso (i.e., if she could not have painted it using a layered</div>
<div>&nbsp;sequence of intervals, one of each color).</div>
<div></div>
<p></p></p><hr/><h3>样例输入</h3><pre>7
0
1
4
5
1
3
3</pre><hr/><h3>样例输出</h3><pre>2
In this example, the interval of color 1 must be painted in an earlier round than the intervals of c
olors 4 and 5, so at least two rounds are needed.</pre><hr/><h3>提示</h3><p>没有写明提示</p><hr/><h3>题目来源</h3><p>Gold</p>
								</div>
							</div>
						</div>
					</div>
				</div>
				
				
			</section>
		</div>
	</main>

	<div class="fbtn-container">
		<div class="fbtn-inner">
			<a class="fbtn fbtn-lg fbtn-brand-accent waves-attach waves-circle waves-light waves-effect" data-toggle="dropdown" aria-expanded="true"><span class="fbtn-text fbtn-text-left">Menu</span><span class="fbtn-ori icon">apps</span><span class="fbtn-sub icon">close</span></a>
			<div class="fbtn-dropup">
				<a class="fbtn fbtn-brand waves-attach waves-circle waves-light waves-effect" href="../list.html" target="_self"><span class="fbtn-text fbtn-text-left">题目列表</span><span class="icon">menu</span></a>
				<a class="fbtn fbtn-green waves-attach waves-circle waves-effect" href="../index.html" target="_self"><span class="fbtn-text fbtn-text-left">返回主页</span><span class="icon">home</span></a>
				<a class="fbtn waves-attach waves-circle waves-effect" href="http://www.lydsy.com/JudgeOnline/submitpage.php?id=4780" target="_blank"><span class="fbtn-text fbtn-text-left">提交代码</span><span class="icon">send</span></a>
				<a class="fbtn fbtn-orange waves-attach waves-circle waves-effect" href="http://www.lydsy.com/JudgeOnline/wttl/wttl.php?pid=4780" target="_blank"><span class="fbtn-text fbtn-text-left">试题讨论</span><span class="icon">chat</span></a>
				
			</div>
		</div>
	</div>

	<!-- js -->
	<script src="../js/jquery.min.js"></script>
	<script src="../js/base.min.js"></script>
	<script src="../js/project.min.js"></script>
</body>
</html>